Hello. The review is not so much of batteries (which, by the way, came out, thanks to Mysku), as a version of reworking a screwdriver. The batteries are of high quality, the capacity is consistent, their implantation instead of nickel-cadmium was successful
Review participants:
High Current LG HE4 Batteries with Gearbest:
The batteries are suitable, their capacity was checked by a friend on the Opus charger, the capacity corresponds. No further special tests were carried out.
Three-channel charger Imax B3:
This is the second attempt to buy such a charger, the first time the order did not arrive, the money was returned. The charge ordered from the seller at the link above has arrived, it works, the set includes a power cord 40 cm long, in the picture the cord is clearly different. There was no cable for connecting charging anywhere in the kit.
Holder for three 18650 batteries:
In the seller's picture, this version of the holder for three 18650s had pins for sealing into a printed circuit board, but a completely different version came to me, not only not for printing, but also with soldered collective farm jumpers connecting all three batteries in parallel. 
Received a partial refund. The jumpers were sealed off, used, although not as originally planned.
Background.
My Interskol DA-12ER-01 screwdriver is almost 10 years old. Most of all he "got" during the renovation of the apartment about 6 years ago, but usually most of the year he took a rest, worked a little in the summer at the dacha, and did small tasks: handicrafts, furniture assembly, etc. Problems with batteries began a couple of years ago, one battery stopped holding a charge, the second worked out quite normally. I then disassembled the defective battery, identified the two most tortured elements, and tried to replace them with similar ones bought on ebay. But when I installed new elements, I found that the rest of the elements, which I considered still alive, were also candidates for the trash can: under load, the voltage across them changed polarity. There was no point in changing all the elements, so I converted this battery into some kind of adapter for connecting a screwdriver to the car's cigarette lighter.
But I was not going to connect it to the on-board network of the car, but to an old lead-acid battery 12v 7ah from a halogen light for a video camera, the socket of which was similar to the socket of a car cigarette lighter. I have long been LED light for video cameras powered by lithium batteries, but the 12V battery remained, so it came in handy for a screwdriver, though it was used only a couple of times. Here is this super-mega adapter:
But since the 12v 7ah battery was already more than 8 years old, it stopped holding a charge, it was not possible to restore it, and I was forced to hand it over for scrap. So most likely I will disassemble the "adapter" for the cigarette lighter, I don't see any sense in connecting the "Shura" to the car.
This summer, the second battery of the screwdriver finally gave up, it began to discharge so quickly that it became impossible for them to perform serious work. In the spring, he still somehow worked, but by the fall, a dozen mediocre self-tapping screws on a single charge became his limit.
But nevertheless, I think that the native batteries of the screwdriver worked very well - they lasted 8 and 10 years for me, while friends died in the 3rd and 5th year, with about the same unprofessional mode of use.
Buying even one new nickel-cadmium battery is a form of savagery, this is 50-60% of the price of such a screwdriver (yes, they are still sold) with two such batteries in the kit. I also rejected the option of buying an already assembled battery of nickel-cadmium batteries from Ali or ebay, ready to be installed in the body of an outdated battery: it is cheaper, but the quality of these batteries is questionable, so, the two cells I bought on ebay had a decent range of capacity, and how much it will all work, it is unknown. In addition, I decided to give up nickel-cadmium completely and irrevocably: the transfer of a cordless screwdriver to lithium, which I did six months ago, has the most positive impressions.
In general, of course, my screwdriver is already old and shabby, so there were thoughts of buying a new, modern one with a lithium battery to replace it. But the mechanical part is still in perfect order, and the mechanics of modern inexpensive shuriks are extremely weak: those that have ever been held in their hands simply had obscene backlashes in the cartridge bearing after an indecently short period of time. And there is no point in buying a professional expensive screwdriver, it will lie in the closet for most of the year.
But most importantly, my hands were itching to remake the screwdriver for lithium myself. At the same time, there were certain doubts: the cost of batteries, protection and charge equalization boards was close to a simple lithium shurik from Leroy-merlin, with a one-year warranty. But the desire to solder and conquer overcame doubts that they would send the left batteries, that something would go wrong, etc.
At first, I wanted to do everything according to the classical scheme, that is, take three high-current 18650 batteries, add a 3S protection and equalization board to them, and accordingly remake the charger for lithium. But then I decided to make it easier, and in my opinion, much more convenient.
Based on my experience with VBG6, F550, F770 and other camcorder batteries, where two 18650 batteries are connected in series, I have long ago concluded that batteries are dying mainly due to the fact that the charge equalization circuit does not cope with its task. As a result, one battery is constantly overcharged, the other is undercharged, and very soon the battery goes to the trash can. Even replacing the dead elements with the original Sanyo, whose parameters are much more stable, did not give an effect as long as we would like, a couple of years and that's it ...
And in a screwdriver, the battery will be of three elements, the current loads are much higher, the imbalance in the capacity of the cells will appear faster, so I very much doubt that the equalization / balancing board will help the batteries not die prematurely. Therefore, I decided to abandon charging all batteries at once from one source, in favor of charging each one separately. The three-channel charger, I decided to take the ready-made, well-known Imax B3, in my opinion it is in any case more efficient than the balancing board, besides, it is very compact and lightweight.
I decided to abandon the overdischarge / overcharge protection board altogether, there is a battery voltage indicator on the screwdriver, it is quite possible to navigate from it how discharged the battery is. Well, if one of the three batteries “play around” and suffers on a par with everyone else (protection against voltage reduction would have cut out the entire battery long ago) ... you know, he has such a fate, he can no longer be helped, but the battery will not turn off ahead of time.
Having estimated that after installing three 18650 cells in the battery case, there will still be a lot of free space in it, I decided to shove the Imax B3 charging itself there. At the same time, to charge the batteries, it will be enough just to connect a 220v cord to the screwdriver. And it's really convenient: no external chargers, only a 220v cord will be included with the screwdriver, and the cord is universal, even from a receiver / printer / music center will do.
No sooner said than done. The first to come to me were batteries from GB, at first I tried to check them myself, putting one at a time in my existing power bank, giving a load of 1A, and calculating the capacity based on the operating time before shutdown. Despite the fact that I recalculated the capacity from a voltage of 5v to a voltage of 3.7v, the results were very underestimated, about 1.5ah, so I asked a friend to check these batteries on a full Opus test charge, I don't remember the model, and he reassured me , the capacity of all the batteries turned out to be normal, however, not 2.5ah, but 2.3ah, which was fine for me.
Initially, I wanted to connect the batteries with spot welding, I even bought a nickel tape for this, but the spot welding unit was never completed. Therefore, I decided to use a ready-made holder for three 18650 cells, ordered, however, for a completely different craft. It did not match the description of the seller, but after a small alteration it did quite fit, especially since the batteries sit very tightly in it, the contacts are thick and hard enough. Even with very dynamic shaking, the batteries did not jump out of the holder.
The last thing that came to me was the Imax B3 charger. I checked it - it works, then I started the process of converting the screwdriver to lithium.
The native battery was gutted, I soldered the wires to the contact group, fixed the battery compartment with screws on the base of the case, and soldered the wires to it. I put a 10A fuse, but I hung it on the terminals: the car holder did not fit into the case. By the way, the contact group is supported by one of the nickel-cadmium elements, it is just the right length. I drove a screwdriver from lithium batteries and wondered how powerfully he was turning now.
Next, I installed the Imax B3 charger in the battery cover, put a charging connector (not native) on the side wall of the cover. I removed the stands of the indicator LEDs, and brought them out into the holes in the case, so that now you can observe the entire charging process through three luminous "eyes". Naturally, red light - charging, green - charged.
Then I connected the charger to the batteries, drove the screwdriver a little, and put it on charge. And here a problem emerged, which I had already read about, and which, in principle, could not be avoided. Chips - TP4056 charge controllers began to heat up wildly. Well, they shouldn't get hot, the charging current (judging by the 1.8k current-setting resistor) is about 600 mA, at the input about 6v. Moreover, I had almost fully charged batteries, the voltage on which during charging was about 4.15v, while a power of about 1.1 watts was dissipated on each microcircuit. This is quite enough for three microcircuits on a small board, and even in a closed volume, to be specifically fried. If the batteries had to be charged from scratch, then even more power would be dissipated on the microcircuits.
Therefore, I replaced the current supply resistors, increasing them from 1.8k to 4.7k, thus reducing the charging current to about 270 mA. Even so, the microcircuits burned their fingers. Of course, nothing terrible happened in this mode, the batteries were charged normally, the green LEDs lit up almost simultaneously. But nevertheless, in extreme heat, the charger may overheat, the case was not closed during the tests. Well, the charge current is somehow too small.
Therefore, I installed a small radiator on the microcircuits (through nomacon), again changing the current setting resistors to 2.2k - the charging current is about 500 mA. Having run charging in this mode, I did not find any serious heating of the radiator, and I am sure that the temperature will be normal in a closed battery case even on a hot day.
The only thing that bothers me is the maximum voltage on the batteries at the end of the charge: 4.20 4.23 4.21v. Isn't that too much? But it is impossible to influence this voltage, except perhaps to replace the microcircuits.
In general, I finally assembled a new battery. Instead of the previous 1.5ah, it has a capacity of 2.3ah, with no memory effect. The downside is that it cannot be left in severe frost, but no one forces you to do this.
Well, I like how the screwdriver works from a new battery.
Now a little about the screwdriver's native charger: 
Charging worked fine for all 10 years, despite the fact that it was heated like an iron. Surprisingly, for 10 years the sharp smell of plastic and burnt getinax has not disappeared from it. Now there is nowhere to apply it, so I decided to gut it:
All the products of the company "Interskol", with which I happened to come across, aroused great doubts that they were made in our country, according to "Interskol" itself. Too much they have everything "in Chinese", and printing, and assembly, and exclusively imported components. Also with the charger, "my" is just zero. I am familiar with domestic production, both consumer goods and military equipment, and I think that in this case everything was done "not according to ours." I think Interskol only glued its labels.
But since the charging is being scrapped, I decided to borrow from it a contact group that was connected to the battery. I disassembled the board and sawed off, leaving a piece with contacts:
The question is why? Yes, in order to be able to connect an external load to the battery instead of a screwdriver. Previously, I had a 12v 7ah battery as a "marching" voltage source, but it died, and it was logical to use a battery for a screwdriver instead. So I made a special adapter from a piece of charging and other materials that came to hand.
The purpose of this adapter with a cigarette lighter plug on the wiring is to power the vehicle's electrical system when removing the starter battery for recharging or replacing it with another battery (I have two of them). I really do not want to restore the settings of the radio tape recorder and other devices after a power outage. Plugged the plug into the cigarette lighter - and do your thing, you can also turn on the dimensions with the emergency gang, and all the settings will be saved. It's a pity that there are no lamps under the hood ... It is not recommended to start the engine with an external battery connected, there is no battery charging current limiter, but in which case the 5A fuse in the plug will blow.
I plan to make the adapter universal in order to connect different devices, but I did not find a suitable connector for myself, I will redo it later.
In general, I am satisfied with the alteration of the screwdriver. It cost me about 1,100 rubles, plus three evenings after work for rework. In my opinion, it turned out conveniently, but, of course, not without drawbacks. The discharge of the battery must be monitored so as not to ditch the batteries, and it is better not to give the converted shura into the wrong hands. But I myself do not yet know exactly how the screwdriver will behave when the battery is discharged to the limit, how much its power will decrease, and what the indicator will show. So it will be necessary to observe the screwdriver in the process of working with it.
I plan to buy +58 Add to favourites I liked the review +61 +114Every craftsman is faced with the problem of reduced tool performance, or complete failure due to the battery. Manufacturers use nickel-cadmium batteries in 12, 14, 18 volt screwdrivers. The sequential assembly of several elements creates the desired voltage. Replacing nickel-cadmium batteries with lithium batteries extends battery life by making construction easier. Mandatory BMS board installation adds reliability. Therefore, the conversion of a screwdriver to lithium batteries, mainly to the 18650 form factor, is justified.
Why do nickel-cadmium batteries fail quickly? In a garland of series-connected cans, each one is special. The chemical process is individual, the charge in closed systems is different. In the event of a malfunction in one bank, the design does not provide the required voltage. The control system and charge balancing in individual components is not provided.
- Each Ni-Cd bank provides 1.2V, and the Li-ion 18650 provides 3.6V.
- The capacity of a lithium battery is 2 times that of a nickel-cadmium battery of a similar size.
- An overheated li-ion battery threatens an explosion and fire, therefore, the installation of control of the uniformity of the charge in the banks is mandatory. BMS is not installed in nickel-cadmium batteries - the manufacturer is not interested.
- Lithium cells have no memory effect, unlike Ni-Cd, they can be charged at any time and within an hour.
- The screwdriver becomes much easier after converting the battery to li-ion, using 18650 cells.
There are only two obstacles to converting a screwdriver for lithium batteries - it is impossible to work with it at minus. The capacity of cans decreases, starting from a decrease already from +10 0 C. Lithium batteries are expensive.
Knowing what input voltage is required for the screwdriver, the charger is reworked, taking into account the placement of the lithium battery cans and control elements in the factory container. You can also do with a flashlight by upgrading the socket for a block of 18650 cells.
Let's say you need to rework a 12 V screwdriver using Ni-Cd cans on li-ion. If you use 3 cans, the output voltage is not enough: 3.6 x 3 = 10.8 V. With 4 components, the power of the apparatus will be higher: 3.6 x 4 = 14.4 V. This will make the instrument 182 g lighter , its power will increase slightly, capacity - solid pluses. But when dismantling, it is necessary to leave the terminals and the native thermal sensor.
Conversion of a screwdriver to lithium batteries 18650 14 V
When converting screwdrivers of different power and flashlights from Ni-Cd to Li-ion, batteries of the form factor 18650 are more often used. They easily fit into a container or a nest, since instead of two or three relatives, one lithium is installed. Alteration of the screwdriver battery should be carried out taking into account the characteristics of lithium 18650 batteries.
This type of energy source does not tolerate deep discharge and excessive charge. Hence, it is necessary to use voltage control boards. Since each battery has its own character, their charge is corrected by a balancer. The point of reworking a screwdriver with a voltage of 14.4 V lies in creating a device using lithium batteries to facilitate a hand tool and increase its performance. Lithium 18650 batteries are most suitable for these purposes.
When selecting components, it should be taken into account that the starting current of the screwdriver is high, it is necessary to select the appropriate BMS for the required number of cans and at least 30 A.
Equipment:
- Lithium-ion cans in the amount of 4 pcs.
- 4-cell li-ion battery controller, CF-4S30A-A works well. It has a built-in balancer that controls the charge of each element.
- Hot melt glue, flux for soldering TAGS, solder.
- Heat-resistant tape;
- Jumpers or thick insulated wire with a cross section of at least 0.75 squares, cut for bridges.
The procedure for converting a screwdriver for 18650:
- Disassemble the case and remove a bundle of 12 Ni-Cd cells from the container.
- Remove the garland, leaving the connector with the “+” and “-” pins. Instead of a temperature sensor, a thermocouple from the controller will be installed.
- Solder the assembly, considering that you cannot use acid, only neutral flux and pure solder. During the connection period, do not warm up the covers. Work pointwise.
- Connect the balancing points to the controller according to the diagram. The connectors are provided on the board.
- Connect the assembly to the plus and minus terminals.
- Check the functionality of the circuit. If everything works, the assembled battery, place the controller in the socket, secure with sealant.
If the charger is not universal, additional alteration will be required. Screwdrivers for 12 V with a universal charger are assembled in the same way, but a protective connection circuit 3x18650 3.7 V for lithium batteries is used. In the same way, a screwdriver is reworked using a set of 18650 batteries in the amount of 2 cells.
Conversion of the Makita screwdriver to a lithium battery
There is a "Makita" screwdriver with a 1.3 A / h battery and a voltage of 9.6 V. To change the power source to a lithium-ion one, you will need 3 18650 components. The alteration will provide the old tool with new possibilities: it will increase the operating time on one charge , will add power as the operating voltage rises to 10.8 V.
The design will require the use of a BMS, a control controller that maintains the lithium cell operating mode within operating limits. With this breaker, each cell will be charged evenly without exceeding 4.2V, the lower voltage is 2.7V. A built-in balancer is used here.
The parameters of the controller should accompany the operation of the instrument when the operating current rises to 10-20 A. The Sony VTC4 30 A board, designed for a capacity of 2100 A / h, can ensure operation without shutdown. Of the 20 amperes, the Sanyo UR18650NSX accepting 2600A / h energies is suitable. The board is needed for 3 elements, which is marked in the 3S classification. In this case, the board must have 2 contacts, plus and minus. If the conclusions are designated with the letters "P-", "P +", "C-", they are intended for later models of screwdrivers.
A step-by-step instruction for converting a Makit screwdriver to lithium batteries looks like this.
- You can disassemble the battery with glue if you tap the junction with a soft-headed hammer while weighing. The direction of impact is downward, into the joint on the lower part of the body.
- Take only the contact plates from the old assembly, carefully disconnecting them from the battery. Leave the sensor and breaker.
- Solder 3 elements in series using TAGS flux and insulated jumpers. The wire cross-section must be greater than 0.75 mm2.
- Assemble the circuit with the controller, and connect the power supply to the contact connectors with 1.5 square wires.
- Check the functionality of the circuit and reassemble the case by placing it on the glue again.
In a screwdriver with an old DC9710 charger, after charging the 18650 lithium battery, the red LED on the panel will turn off. The built-in controller monitors the charge level.
Makita DC1414 T charger is used to charge 7.2-14.4 V power sources. While charging is in progress, the red light is on. But when charging a lithium battery, its voltage does not fit into the standards of salt products, and after 12 V the charger will flash red and green. But the necessary charging is already there. The screwdriver is ready for use.
Conversion of the 12 V Hitachi screwdriver to 18640 lithium batteries
Features of the conversion of the 12 V Hitachi screwdriver for lithium batteries. The very compact battery compartment is designed for finger cells. Therefore, you should prepare a place for 18650 cells. It is necessary to cut one side of the partition in order to tightly place 1 element.
You need to get a gumboil, a flat metal connecting tape, hot glue. It is necessary to install lithium batteries in a screwdriver during alteration through a protective controller. It should serve 3 18650 cells, 3.7V, and rated for 20-30 amps.
Remove the old battery from the socket, carefully disconnect the contacts in the assembly with the temperature sensor and the power-on indicator. Clean up and sign contacts. They should be brought out to one side, connected with solder to the leads from thick wires and filled with hot melt glue over the assembly.
Assemble a power source with one of the 3 cell controllers. Build a serial circuit of 3 Li-ion cells. Connect the controller. The conversion of the 12-volt lithium battery is completed when the structure is installed in the unit, secured, and the charging indicator lights up. After fully charging, the measurements show 12.17 volts in the external network. But this is enough for trouble-free long-term operation of the device.
Alteration of the Interskol screwdriver for lithium batteries 18650
Sooner or later, the nickel-cadmium assembly of 15 cans fails. One or two elements are lazy, and it is no longer possible to get the voltage at the output. Modern DSh "Interskol" on lithium batteries serve much better. The craftsmen have mastered the alteration of the screwdriver for 18 volt lithium batteries.
It is necessary to purchase a protection board for 5S, 3.7 V and 40-50 A. You will need a balancing board and the energy sources themselves - 5 lithium 18650 batteries, you can leave them with factory thermistors by extending the wires. During installation, create a contact pad, insert the assembly, check the functionality, secure. The assembly features of the wizard's advice are given in detail in the video. See here for full details on reworking an 18-volt lithium screwdriver
The rapid degradation of cordless tool batteries is a real scourge. Almost always, the life of the screwdriver itself exceeds the service life of Ni-Cd cells and you either have to buy spare batteries or say goodbye to the tool. Today we will talk about the main way to extend the life of the battery.
18650 battery - why it is
Repairing power tool batteries usually involves restoring the electrolyte of the nickel-cadmium "cans" or replacing them altogether. The idea of changing one type of energy element to a more perfect one is quite sensible. This eliminates a wide range of battery-powered tool problems, including heavy weight, small capacity, memory effect and poor cold holding capacity.
However, why should it be exactly 18650 batteries, and not some others? The answer is simple: this is the most common type of battery, except perhaps for batteries for mobile phones or other gadgets. The latter are quite possible to use, but most of them carry a built-in charge controller on board, and this is an extra waste of money.
In addition, the batteries must be high-current, that is, capable of supporting a load of 70-100 watts. Batteries for electronic cigarettes made by Samsung or LG are optimal. You should not take products from an unknown manufacturer: after all, Li-ion is a rather powerful thing and the low quality of the power cell case can provoke a loss of tightness from overheating with all the consequences. And if there are half a dozen more batteries in the neighborhood, the consequences can be very dire.
You can buy batteries on Aliexpress or other Chinese online stores, where they are quite cheap (200-250 rubles apiece, cheaper in bulk). In parallel, you need to purchase a number of additional lotions, this is due to the specifics of working with lithium batteries. Well, what are these gadgets and what is the point of using them - we will tell you in the course of the description of the alteration.
Disassembling the case
The first step is to disassemble the battery case into two halves. The easiest way to do this is if the battery pack is tightened with 4-5 screws: just unscrew them and pull out the upper part.
If the battery case is glued together (Makita, AEG), then the hassle will significantly increase. We lay the battery on its side and carefully tap the glue seam with a rubber mallet. The blows are accurate, not strong, and frequent. We beat off the joint evenly around the perimeter and try to stretch the halves every 50-100 strokes. Even the most stubborn corps surrender in 10-15 minutes of such "execution".
Next, we throw away the unnecessary parts of the content. The terminal block must be carefully torn off the two upper cans so that two nickel tongues remain on it. Looking ahead, we say that usually, when reworking, a new package of batteries is welded together by contact welding in the manner of factory ones. This is a cool solution, but not everyone wants to build a welding machine. Therefore, leave the length of the strips so that the wires can be fixed to it with two small bolts, and the rest of the elements will be connected by soldering.
In any convenient part of the case, you also need to make a hole for the JST-XH balancing connector. On the outside with an awl we mark a rectangle 6 mm high and 15 mm wide for a 12 V battery voltage or 20 mm for a 18 V voltage. Insert the connector into the hole made and fix it with hot glue or epoxy.
How to place items
Unlike Ni-Cd or Ni-MH cells, lithium batteries have a higher capacity and voltage, so fewer of them will be included in the battery. The dimensions of the 18650 cell are 65mm height and 18mm diameter. Initially, check how many of them will fit in an empty case, and determine the layout, if necessary, cut off the interfering stiffeners.
If the battery pack has a protruding top, a pair of cells will fit into it. Another one is convenient to put on its side right under the two vertical ones. In the remaining space, you can put another 5 to 7 batteries. If the battery has a charging slide, stack the cells across the case in two stacks.
The voltage of the Li-ion battery is 3.7 V, but under load there is a drawdown of about 10-12%. This means that for a 12 V screwdriver you need at least 4 batteries, and for an 18 V - at least 5 pcs., Although it is better to use 6, because a lot is not a little. Do not worry that the engine will be "frightened" by the high voltage and will make you live for a long time. With a drawdown under load, the overvoltage will be minimal and well within the operational limits. You need to decide on the number of batteries before you embed a balancing connector into the case, because there should be one more contacts in it than there are elements in a serial connection.
Now about the capacity. For lithium cells, it ranges from 2.5 to 3 A / h, which in itself is not bad. To double the capacity, you will need to double the number of batteries, but it's definitely worth it. The only thing that can stop you in this venture is the size of the battery pack. In any case, remember that the number of elements must be strictly multiples of 4, 5 or 6, depending on the voltage.
When you put the batteries in the right order, fasten them together with electrical tape and achieve complete immobility of the elements inside the case by filling the remaining space with pieces of expanded polystyrene or polyurethane foam. There is no need to leave space for the wires; in extreme cases, during the final assembly, you will need to perform a couple of additional undercuts.
Battery connection diagram
To get the cherished 12 or 18 V, the elements must be connected in series. That's it, no tricks, just observe the polarity. The minus of each battery is connected to the plus of the next one, the outer two wires are connected to the terminal block.
If you double the capacity, not individual batteries are connected in series, but assemblies of 2 cells. In each assembly, the positive contact is connected to the positive neighbor, the same is the case with the negative ones.
So that in the end the jumpers between the batteries do not intertwine into an indistinct cobweb, think over the connection scheme in advance. It is most convenient to solder the batteries when they are already wound in a tight bundle, choose the minimum length of the jumpers.
For soldering, the contacts of each battery should be well tinned. First, clean them with a file or fine sandpaper, removing the top nickel layer. Use phosphoric acid as a flux, the most common solder is POS-61 with rosin. The soldering iron must be powerful, 60 W, no less. It is strictly forbidden to overheat lithium batteries, the contact time with the sting is no more than 2 seconds. Therefore, first we tinker, let it cool, then we solder.
Also, pre-tin the jumpers from a stranded conductor of 2.5 mm 2 and supplement them with balancing wires so that one wiring falls on each node between parallel-connected batteries or groups. The length of the wires - to reach the balancing connector in the case, the cross section is about 0.5 mm 2.
When soldering, the tinned core of the jumper is first heated, then it is brought to the contact of the battery until the solder melts on it. During cooling, you can press down the seam with a wooden chip. And do not spare the tin - the connection must be very reliable. Also, do not forget to wash off the remnants of the flux, otherwise after six months or a year of operation, all efforts will go to waste. Rinse the intricate positive contact with particular care; rubbing alcohol or acetone can be used to remove it.
If you try to solder the outermost wires of the battery to the nickel contacts of the shoe, you will most likely ruin it hopelessly by overheating the plastic. It is much better to drill two holes with a diameter of 3-4 mm and tighten the veins to the plates with a couple of small screws. Here it is convenient to use slats with double holes, which were plucked out of old Soviet forks in large quantities.
Along with the outermost wires of the battery bundle, screw on a couple more balancing wires. The resulting balancing cable must be soldered in a specific order. From the datasheet on the connector, determine its contact, numbered with one, and solder a wire from the positive terminal to it. Next, follow the battery chain and solder the wires in series, one after the other, completing by connecting the last contact to a common negative core.
What and how to charge
The peculiarity of charging a bundle of Li-ion batteries is that they must be charged strictly evenly. Otherwise, one of the elements loses in the depth of charging and, due to the low voltage, begins to squander the rest, discharging even more. In lithium screwdriver batteries, as in laptop batteries, special charge controllers are provided.
Therefore, the most important and expensive purchase for you will be a universal charger. Best of all, if it is something from the SkyRC line - these devices have already repeatedly proven that they are worth the money spent. You can take a Chinese counterfeit for 300-600 rubles cheaper, but always with the function of charging Li-ion batteries with several cells. Do not worry about the high cost: such a thing should be in the arsenal of every homemade product, it will help restore and properly charge old dead batteries, including lead-acid ones, and Ni-Cd cans recently removed from the battery pack.
To charge a converted battery, you need to redo the standard charger. The task is simple - to solder two charging wires to the main terminals, observing the polarity. The balancing connectors are connected by a male-to-male wire, the device is set to the desired mode and a fully automatic charging process is carried out. The main thing in the operation of such a battery is not to take the elements into a deep discharge, but usually the engine noticeably loses power long before such a significant voltage drop, so you will hardly be able to hopelessly kill new batteries.
Has the meaning. The advantage is that they have a high electrical density. As a result, by installing such a device in a screwdriver body, we can achieve an increase in the duration of the tool many times over. The charging current for high-power lithium batteries, especially for new modifications, can reach 1-2 C. Such a device can be recharged in 1 hour, without overstating the parameters recommended by the manufacturer and without spoiling the quality of the product.
What do lithium batteries look like?
Most lithium devices are housed in a prismatic case, but some are cylindrical in shape. These batteries use roll electrodes and separators. The body is made of aluminum or steel. The positive pole faces the housing cover.
In prismatic configurations, the electrodes are rectangular plates. To ensure safety, a device is provided in the battery that acts as a regulator of all processes and opens the electrical circuit in critical situations. Increased sealing of the case does not allow electrolyte to flow out and oxygen and moisture penetrate inside.
What measures should be taken to avoid damaging the lithium battery?
- Due to the limitations of technology, the charge indicator of lithium batteries should not be higher than 4.25-4.35 V. The discharge should not reach 2.5-2.7. This condition is indicated in the technical data sheet for each specific model. If these values are overestimated, you can damage the device. Special controllers are used for charging and discharging, which keep the voltage on the lithium cell within the normal range. Converting the screwdriver to a lithium battery with a controller will protect the device from malfunction.
- The voltage rating of lithium batteries is a multiple of 3.7 V (3.6 V). For Ni-Mh models, this figure is 1.2 V. This phenomenon is understandable. in lithium devices it is stored in a separate cell. A 12 volt lithium battery will never be assembled. The rating will be 11.1 V (three cells in series) or 14.8 V (four cells in series). In addition, the voltage indicator of the lithium cell changes during operation when fully charged by 4.25 V, and when fully discharged by 2.5 V. The voltage indicator 3S (3 serial - three serial connections) will change during the operation of the device from 12.6 V (4.2x3) to 7.5 V (2.5x3). For a 4S configuration, this figure ranges from 16.8 to 10 V.
- Converting a screwdriver to 18650 lithium batteries (the overwhelming majority of products have this size) requires taking into account the difference in dimensions with Ni-Mh cells. The diameter of the cell 18 650 is 18 mm and the height is 65 mm. It is very important to calculate how many cells will fit in the case. It should be remembered that for a model with a power of 11.1 V, you will need the number of cells in multiples of three. For the 14.8 V model, four. The controller and commutation wires must also fit.
- The lithium battery charger is different from the Ni-Mh charger.
The article will consider how the screwdriver is converted to lithium. The tool is equipped with a pair of Ni-Mh rechargeable batteries with a voltage rating of 12 V and a capacity of 2.6 Ah. The rework of the Hitachi screwdriver will be considered. Lithium batteries will provide the instrument with a long service life.
Choosing the rated voltage
First of all, you should decide on the choice of the voltage rating indicator for a lithium-based device. The choice should be made between the 3S model (its voltage range is from 12.6 to 7.5 V) and the 4S-Li-Ion battery (the voltage range is from 16.8 to 10 V).
Advantages of the second option
The second option is more suitable, because the voltage in the battery drops quite quickly from the maximum to the minimum (from 16.8 to 14.8 V). For an electric motor, which, in fact, is a screwdriver, an excess of 2.8 V is not a critical mark.
The lowest voltage indicator is for the 3S-Li-Ion modification. It is equal to 7.5 V, which is insufficient for the normal functioning of the electrical device. By mounting four configurations, we will increase the battery.
How to decide on the choice of lithium cells?
In order to make the selection of lithium-based cells, the limiting factors should be outlined. Currently, lithium devices are produced with a permissible load current of 20-25 A.
Pulse current values (short, up to 1-2 seconds) reach 30-35 A. The configuration of the battery will not be violated.
How many cells will fit in the case?
Assembling 4S2P (four serial connections and two parallel) will not work. Converting a screwdriver to 18650 lithium batteries assumes the presence of eight cells. How can they meet four? Each cell will carry the maximum current load.
How to determine the maximum current in a screwdriver?
Converting a 12V screwdriver to lithium batteries involves connecting the device to a laboratory power source with a maximum current of 30 A. The limiter regulator is set to the maximum value. Having created the voltage level of the power source close to the nominal value of the future battery, we begin to smoothly pull the trigger. The current that is consumed by the screwdriver will rise to 5 A. Now you should sharply pull the trigger. This will short-circuit the power supply. The current will reach a power of 20-30 A. Perhaps, its indicator would be much higher, but the power of the power supply will not allow fixing it. This will be a short load current with a sharp pull on the trigger of the screwdriver. Any model of such a device will react in the same way.
Next, clamp the tip of the screwdriver with a vise and observe to what value the current consumption will increase during operation, when the ratchet is triggered in the screwdriver. The current indicator in this case increases to 10-12 A.
So you can determine the magnitude of the load current. In this case, it will be equal to 5 A at idle and 30 A at a sharp start, and at maximum load it will be 12 A. The manufacturer must choose lithium cells, the nominal load current of which will be 10-20 A, and the pulse one - 25-30 BUT.
How to choose a controller?
So, the screwdriver is being converted to lithium batteries. A regular charger is required for the device. When choosing a controller, keep in mind that the device must meet two parameters:
- an indicator of the rated operating voltage;
- indicator of the rated operating current.
With the voltage, everything is very clear: if the battery is 11.1 V, then the controller will be with the same voltage.
Rated operational current refers to the protection capacity of the board. Thus, a 4 A controller is designed for a current mark of 4 A, and with an indicator of 8 A, an additional load falls on it. In this case, the protective device will be triggered. All these technical data are stated in the passport of each controller modification. In this case, one modification can have a limiting current indicator of 30 A, and the other - 50 A. And both of these devices will formally be suitable for operation. Also, when creating a lithium battery, there is a limitation in size. Therefore, you should purchase a controller that will fit in the old battery case.
Disassembly and assembly
Converting a screwdriver to lithium batteries includes the following steps:
- Open the old battery by unscrewing the five screws.
- Remove the Ni-Mh battery from the housing. It will be noticeable that the contact pad engaging with the contact group of the screwdriver is welded to the negative contact of one of the Ni-Mh cells. The welding points should be cut using a tool with a cut-off stone built into it.
- Wires are soldered to the contacts, the cross-section of which is at least 2 mm 2 for the power terminals and 0.2 mm 2 for the thermistor. The contact pad is glued to the battery case with hot melt glue.
- According to the indicator of internal resistance, four cells are selected on the meter. The value should be the same for all four fixtures.
- Lithium cells are glued with hot melt glue so that they are compactly located in the housing.
- Welding of cells is carried out on a resistance welding machine using a nickel welding tape (its cross-sectional index should be equal to 2X10 mm).
Installing the protection board
This step can show how lightweight the lithium battery is. The weight of the Ni-Mh device was 536 g. The weight of the new lithium device is 199 g, which will be quite noticeable. In weight, we managed to win 337 g. At the same time, an increase in energy capacity is observed.
The battery is mounted in the housing. The voids are filled with soft material from the packaging.
Connecting to a screwdriver
- A sharp pull on the trigger provokes the activation of the protective current mechanism. But in fact, such a protective mode is unlikely to be needed when using the tool. If you do not specifically provoke protection, then the work of the screwdriver will be stable.
- The tip should be clamped in a vice. The battery power freely triggers the ratchet, which limits the increase in the number of torsion revolutions.
- the screwdriver discharges to The discharge current should be 5 A.
- The battery is inserted into the standard charger. The charge current indicator when measured is 3 A, which is acceptable for lithium cells. For the LG INR18650HG2 configuration, the maximum charge current will be 4 A, which is indicated in the technical specification.
How long does it take to replace the batteries?
Converting the screwdriver to lithium batteries will take approximately 2 hours. If all parameters are checked, then it will take 4 hours.
Everything can be done on your own, without the help of another person. But contact welding and selection of batteries cannot be carried out without specialized equipment.
What else can you test the state of charge besides the controller?
The screwdriver was converted to lithium batteries. The built-in charger is ideal. But the cost of the controller is quite high. The device will cost $ 30, which is equivalent to the cost of the battery itself.
To test the charge level of a lithium battery on the go without using a charger, you can use the special RC helicopter lipo battery AKKU portable voltage meter tester alarm 2-6S AOK. The cost of the device is very low. It has a balance and charge connector similar to the iMax6 device. The device is connected to the battery via an adapter. This voltage level monitor is very convenient. It can measure from two to six lithium cells connected in series, and also give the total indicator or the voltage of each element separately with extreme accuracy.
How much will it cost to replace Ni-Mh with a lithium device?
How much money will be required to convert a screwdriver to a lithium battery?
The price for such a device consists of the cost of several components:
- the configuration of a 4S-battery based on lithium costs 2200 rubles;
- the purchase of a controller for charging and discharging plus a balancer costs 1240 rubles;
- the cost of welding and assembly is 800 rubles.
It turns out that a self-made lithium battery costs 4240 rubles.
For comparison, let's take a similar configuration from factory-made lithium. For example, the Makita 194065-3 device is designed for a screwdriver. It has similar parameters. The cost of such a device is 6500 rubles. It turns out that converting a screwdriver to lithium batteries saves 2300 rubles.
The cordless tool is more mobile and easier to use than its networked counterparts. But do not forget about the significant drawback of a cordless tool, this is how you yourself understand the fragility of batteries. Buying new batteries separately is comparable in price to purchasing a new tool.
After four years of service, my first screwdriver, or rather batteries, began to lose capacity. To begin with, I assembled one of two batteries by choosing working "banks", but this upgrade did not last long either. I reworked my screwdriver on a network - it turned out to be very inconvenient. I had to buy the same, but new 12 volt "Interskol DA-12ER". The batteries in the new screwdriver lasted even less. As a result, two serviceable screwdrivers and more than one working battery.
On the Internet, they write a lot on how to solve this problem. It is proposed to convert old Ni-Cd batteries to Li-ion batteries of the size 18650. At first glance, there is nothing complicated about that. You remove old Ni-Cd batteries from the case and install new Li-ion. But it turned out to be not so simple. Here's what you should look out for when upgrading your cordless tool.
For alteration you will need:
I'll start with 18650 lithium-ion batteries.
The rated voltage of the 18650 cells is 3.7 V. According to the seller, the capacity is 2600 mAh, the marking is ICR18650 26F, the dimensions are 18 by 65 mm.
The advantages of Li-ion batteries over Ni-Cd are smaller dimensions and weight, with a higher capacity, as well as the absence of the so-called "memory effect". But lithium-ion batteries have serious drawbacks, namely:
1. Subzero temperatures drastically reduce capacity, which cannot be said about nickel-cadmium batteries. Hence the conclusion - if the tool is often used at low temperatures, then replacing it with Li-ion will not solve the problem.
2. A discharge below 2.9 - 2.5V and an overcharge above 4.2V can be critical, a complete failure is possible. Therefore, a BMS board is needed to control the charge and discharge, if it is not installed, then the new batteries will quickly fail.
The internet mostly describes how to remake a 14 volt screwdriver - perfect for retrofitting. With a series connection of four 18650 cells and a nominal voltage of 3.7V. we get 14.8V. - just what you need, even with a full charge plus another 2V it is not scary for the electric motor. And what about a 12V instrument. There are two options, install 3 or 4 18650 cells, if three is not enough, especially with a partial discharge, and if four is too much. I chose four and, in my opinion, made the right choice.
And now about the BMS board, it is also from AliExpress.
This is the so-called charge control board, battery discharge, specifically in my case CF-4S30A-A. As you can see from the marking, it is calculated for a battery of four 18650 cells and a discharge current of up to 30A. It also has a built-in so-called "balancer", which controls the charge of each element separately and eliminates uneven charging. For the correct operation of the board, the batteries for assembly are taken of the same capacity and preferably from the same batch.
In general, there are a great many BMS boards on sale with different characteristics. I do not advise taking for currents below 30A - the board will constantly go into protection and to restore operation, you need to briefly apply a charging current to some boards, and for this you need to remove the battery and connect it to the charger. There is no such drawback on the board that we are considering, you just release the trigger of the screwdriver and in the absence of short-circuit currents, the board will turn on by itself.
For charging the converted battery, the native universal charger was perfect. In recent years, Interskol has begun to equip its tools with universal chargers.
The photo shows to what voltage the BMS board charges my battery together with a standard charger. The voltage on the battery after charging 14.95V is slightly higher than that required for a 12-volt screwdriver, but it is rather even better. My old screwdriver became faster and more powerful, and fears that it would burn out, after four months of use, gradually disappeared. That seems to be all the main nuances, you can start reworking.
We disassemble the old battery.
We solder the old cans and leave the terminals together with the temperature sensor. If you also remove the sensor, then when using the standard charger, it will not turn on.
According to the diagram in the photo, we solder 18650 cells into one battery. Jumpers between the "banks" must be made with a thick wire of at least 2.5 kV. mm, since the currents during the operation of the screwdriver are large, and with a small cross-section, the power of the tool will sharply drop. The network writes that it is impossible to solder Li-ion batteries because they are afraid of overheating, and they recommend connecting using spot welding. You can only solder you need a soldering iron of at least 60 watts more powerful. The most important thing is to solder quickly so as not to overheat the element itself.
It should look something like this to fit into the battery case.
